Steamed chocolate sponges

Name: Steamed chocolate sponges
Prep time: 10 min
Cook time: 40 min
Total time: 40 min
Yield: 8 portions
Ingredients: 100 gram vegetable oil; 170 g white sugar; 85 g Greek-style natural yoghurt; 2 eggs; ¾ tsp natural vanilla extract; 115 g plain flour; 60 g unsweetened cocoa powder; 1 tsp instant coffee; ½ tsp bicarbonate of soda; ¼ tsp sea salt; 500 g water